As was noted in copending application Ser. No. 745,055, now U.S. Pat. No. 4,621,529, by the inventor of the present application and assigned to the same assignee, conventional guidance systems for aircraft and missiles use multisensor assemblies for sensing angular rates about some axis perpendicular to the spin bearing axis of the device. A multisensor assembly includes a gyroscopic element restrained by a piezoelectric crystal beam to a base of the assembly. As is well known, a mechanical distortion of a piezoelectric crystal beam would produce a corresponding electrical signal. Thus, for a multisensor assembly, by appropriately restraining the gyroscopic element to the base via a piezoelectric crystal beam, an angular rate of the gyroscopic element--in relation to the base--can be ascertained from the electrical signal generated by the piezoelectric beam. As was discussed in the aforesaid copending application, restrained piezoelectric crystal beams may also be used for determining linear accelerations along any axis perpendicular to the spin bearing axis of the multisensor assembly.
In the copending application, the piezoelectric crystal beam used to restrain the gyroscopic element to the base of the multisensor assembly has the shape of a trapezoid. This trapezoidal piezoelectric crystal beam is held by two clamps to the gyroscopic element and the base of the multisensor assembly.
Insofar as the operation of the multisensor is concerned, the trapezoidal beam does impart a restraining torque to the gyroscopic element. However, from repeated usage, it was found that there are two problems associated with the use of the trapezoidal piezoelectric crystal beam in a multisensor assembly. The first problem arose due to the fact that the clamps and the piezoelectric crystal have different coefficients of expansion, thereby causing a mismatch to exist between the two different materials. Consequently, the piezoelectric beam tends to crack. The second problem found is that vibrations from the spindles and the bearings of the multisensor assembly are transmitted to the gyroscopic element. These vibrations are in turn transmitted to the piezoelectric crystal beam. Consequently, a relatively large amount of noise which places a limit on the performance of the multisensor assembly is present in the copending application device.